Apparatus for manufacturing wallboard joint tape



March 1954 E. P. THORSELL 2,

APPARATUS FOR MANUFACTURING WALLBOARD JOINT TAPE Filed NOV. 10, 1951 3 Shets-Sheet l HrroP/wr.

March 1954 E. P. THORSELL 2,671,991

APPARATUS FOR MANUFACTURING WALLBUARD JOINT TAPE I Filed Nov. 10, 1951 3 Sheets-Sheet 3 1 7' iii/ 36' 7.10.

-12 I 57 v I IN VEN TOR. 51: W42? 7? 7710mm: .4

HTTOP/VL' K Patented Mar. 16, 1954 APPARATUS FOR MANUFACTURINQ WALLBOARD JOINT TAPE Edward P. Thorsell, Manchester, Conn., assignor to The Marvan Corporation, West Hartford, Conn., a corporation of Connecticut Application November 10, 1951, Serial No. 255,859

4 Claims.

This invention relates to an apparatus for manufacturing wall board joint tape such as described in the co-pending application of Lou C. Reed, Serial No. 159,165, filed May 1, 1950.

It is an object of the present invention to provide an improved apparatus for more efficiently and accurately grindin wall board tapes and which will greatly facilitate the threading of the tape through the apparatus and the adjustment of said tape with relation to the grinding wheels.

It is a further object of this invention to provide improved means for dressing the grinding wheels of the apparatus in such a manner as to automatically provide a predetermined degree of taper on said Wheels.

Further objeotsand advantages of the invention will be more clearly understood from the following description and from the accompanying drawings in which:

Fig. 1 is a side view of a portion of the apparatus embodying my invention.

Fig. 2 is an enlarged rear view of the grinding head and tape supporting mechanism.

Fig. 3 is a plan View of the tape supporting mechanism.

Fig. 4 is a side view of said mechanism, partly in central vertical section.

Fig. 5 is an enlarged diagrammatic view illustrating the tape grinding operation by one set of grinding Wheels.

Fig. 6 is a similar view illustrating the operation by the succeeding set of grinding wheels.

Fig. 7 is a similar view on a further enlarged scale.

Fig. 8 is a cross-sectional view of the completed tape.

Fig. 9 is a side view of the grinding head showing my improved means for dressing the grinding wheels of said apparatus.

Fig. 10 is a sectional front view thereof.

Fig. 11 is an enlarged front view illustrating the operation of the wheel dressing device.

Fig. 12 is a sectional front view thereof.

Fig. 13 is a diagrammatic view illustrating, in an exaggerated manner, the principle of said wheel dressing device.

In the embodiment illustrated in the accompanying drawings, the numeral 5 denotes a suitable support or table upon which there is mounted a pair of grinding units for grinding the opposite sides of the tape 6 which is fed through the apparatus from a roll 7.

Each of the grinding units comprises a stationary base 8 which is secured to the table 5 and carries thereon a movable base 9 that is slidable on said stationary base in a direction parallel to the axis of rotation of the grinding unit; the said movable base being slidably secured to the stationary base by means of a dove-tailed connection as indicated at H].

A carrier base I I is slidably mounted upon the movable base 9, also by means of a dove-tailed connection, shown at l2, and is movable in a direction perpendicular to the axis of rotation of said grinding wheels. The said carrier base has pairs of opposed upright projections 13 and 14 at its opposite ends. A supporting plate [5 is pivotally mounted between the upright projections [3 at one end by means of a shaft l6, and the opposite end of the said supporting plate rests upon a positioning bar I1 which is rotatable by means of a handle i'l-a and has a cam portion It for supporting the plate IS in a predetermined position.

Upon the supporting plate [5 there is slidably mounted a wedge-shaped adjusting member l9 which supports a tape supporting table having a pair of shoes 2i-2l upon which the tape rests as it is passed over the said tape supportin table during a grinding operation; the said table being provided with suitable rollers 23-23, at the opposite ends thereof, for leading the tape onto and off of the said table and pairs of opposed guide bars 2fi--2d which are adjustably mounted on the table so as to guide the tape and retain it upon the shoes 2i-2l as it passes through the apparatus.

The adjusting member I9 is moved longitudinally by means of an adjusting screw 25 which is threaded to said member and has a graduated head 26 by means of which the screw may be rotated. The supporting table 20 is secured against longitudinal movement, relatively to the supporting plate I5, by means of a post 2'! which fits snugly in the table 28 and the said supporting plate and has a clamping screw 28 threaded thereto that cooperates with a washer 29 to rigidly clamp the work table Zll in adjusted position upon the supporting plate.

Each of the grinding units includes a pair of grinding wheels 36-30 which are carried on a spindle that is rotatably mounted in a grinding ead 32 that is rigidly mounted upon the base 8 and the said grinding wheels may be driven in any conventional manner.

In the illustration of Fig. 1, the numeral 33 indicates the position of the grinding wheel of the second grinding unit which includes the rollers indicated at 34 -34; the tape 6 being reversed, as indicated at G-a, as it moves into the plate to be lowered and thereby lower the Work supporting table away from the grinding wheels 3U3ll. The tape is then threaded over the first roller 23, between the guide bars 24-24 and over the supporting shoes 2l--2I, then over the second roller 23 and downwardly therefrom around an idler roller, not shown. After the said idler roller, the tape is turned so that it is reversed, as indicated at ii-a, and then threaded through the second grinding unit of the apparatus in the same manner as above described.

'When the tape has been thus threaded through the grinding units and the grinding wheels are in rotation, the tape is brought into contact with the grindin surfaces of the wheels by simply rotating the supporting bar I? of each unit so that the cam portion !8 thereof will swing the supporting plate 15 upwardly about its pivot and thereby move the work table 29 upwardly and bring the tape thereon into contact with the grinding surfaces of the Wheels.

As the tape moves through the apparatus, the marginal edge portions of one side thereof will be ground to a taper by the tapered grinding wheels --3D, as illustrated in Figs. 5 and 7, so that the said edge portions will be bevelled-as illustrated in Fig. 5. As the said tape travels through the second grinding unit the opposite side thereof will be ground so as to produce a tape with marginal edge portions which are bevelled on. both sides to provide thin .free edges.

When it is desired to raise or lower the table 2i} so as to adjust its relation to the surfaces'of the grinding wheels in order to vary the degree to which the tape is ground and thereby increase or decrease the thickness of the free edges of the I tape, the clamping screw 28 is first loosened and the adjusting screw 25 is then rotated by its head 26 so as to slide the wedge-shaped cam member It in the proper direction for the adjustment which is to be made. ment has been made, the clamping screw 28 .is again tightened so as to retain the table in the adjustment position.

'It will be understood from the above description that the improved tape grinding units provided.

by my invention greatly facilitates the adjustment of the tape with relation to the grinding wheels and permits withdrawal of the work supporting table from its normal operating position with relation to the grinding wheels, and its return thereinto, without requiring disturbance of the adjustment that was previously made for said table.

Each of the grinding units may be further adjusted longitudinally by loosening the set screws and moving the carrier 13 on the movable base 9, and laterally by loosening the set screws 35-11 and moving the said movable base with the unit thereon upon the base 8.

My invention also includes the provision of suitable means for easily dressing the grinding wheels of my improved apparatus and forming a predetermined degree of taper thereon in accordance with the degree of taper that it isdesiredto obtain through the grindingoperation.

When the desired adjuston the bevelled marginal edge portions of the tape.

As illustrated in Figs. 9 to 13, the said dressing mean is incorporated in a device which includes a base 36 that is secured upon the side of the grinding head 32 by means of screws 31-31. A carrier arm 38 is pivotally mounted :upon the said base 36 by means of a-=- shouldered stud 39 and the said arm carries a holder 40 upon which is mounted a dressing tool having a shank 4| which is threaded to and extends through the .ho'lder40. The said dressing tool has a suitable cutting tool, such as a diamond point 42, or the like, mounted in the end thereof and a head 43 by meansof which the said shank may be rotated for the adjustment of the cuttin tool relatively to the grinding wheels. The arm G0 is adjustably secured to the carrier arm 38 by means of a screw 44 which extends through a slot 45 in said carrier arm.

In its normal position, the said dressing device maybe as shown in Fig. 9 wherein the carrier arm 38, with the dressing tool thereon,-hangs downwardly between the grinding wheels -30-30 without interfering with the grinding operation of the apparatus. When it is desired todress the grinding wheels, the operator merely grasps the head 3 and swings the cutting .tool about the axis Bil-a of the pivot screw 139 onan-arc 46 which has its center upon said axisand lies in a plane that is parallel to the axis 41 of thegrinding wheels.

As the cutting tool is swung across the' faces of the grinding wheels'on the are 46, the said cutting tool will be carried farther away from the axis 4?, in a plane parallel to the vertical plane as, as it moves towards the far sidesof the wheels and thereby dress each of said wheels to a diameter which increases towards the 'far side thereof and thus provide the predetermined taper which is required onsaid wheels for bevelling themarginal portions of the tape'during agrinding operation.

It will be clearly seen'from Fig. 13 of the drawings that the point 49, where the are 46 intersects the plane of the far side'of the *wheel, is farther from the axis 47 of the wheel than the point 46 where the-said arc intersects'the plane of the near side of the wheel. This dresses the wheel with the smaller diameter Skat its near side and the larger diameter 52 at its far side and thereby provides the taper on said'wheelon a straight line as indicated at 53.

It will be noted that the dressing device may be adjusted for dressing the wheels'atany-desired taper by changing the radius of the M046. This may be done by means of the adjusting screw 44. or by inserting the stud 39 into either of the threaded holes 39-?) or-39-c to thereby change the radius-of thearc 46 and the movement of the cutting tool d2 relatively to the faces of the grinding wheels. The said threaded holes will also permit adaptation of the dressing device to grinding wheels of-diiferent diameters.

I claim:

1. Apparatus for reducingmarginal'portions of a tape including a pair of co-axial spaced grinding wheels, a mechanism for supporting the tape relatively to said grinding wheels; the said supporting mechanism comprising a stationary base positioned under the said grinding wheels, a carrier base mounted on said stationary base and adjustable longitudinally and transversely thereof,a supporting memberpivotally mounted on said carrier base, a supporting .table mounted -:on

said supporting member for supporting the tape in contact with the grinding wheels, a wedgeshaped adjusting member positioned between said table and supporting member, an adjusting screw anchored on said supporting member for moving said wedge-shaped member to vary the position of the supporting table relatively to the supporting member and to the grinding wheels to thereby vary the degree to which the said tape is ground, a stud securing the table to the supporting member against displacement relatively thereto and permitting adjustment by said wedge-shaped member, and a bar rotatably mounted on said carrier base and having a cam-shaped portion for positioning the said table relatively to the grinding wheels; the said cam-shaped portion permitting withdrawing and returning movement of the tape supporting table relatively to the grinding wheels without disturbing the adjustment of said table with relation to said wheels.

2. In an apparatus for reducing the marginal edge portions of a tape including a pair of coaxial spaced grinding wheels, a supporting mechanism for supporting the tape with the marginal portions thereof in contact with said grinding wheels for a grinding operation; the said supporting mechanism comprising a stationary base positioned under said wheels, a carrier base mounted on said stationary base and adjustable thereon transversely and longitudinally, a supporting member pivotally mounted on said carrier base, a supporting table carried on said supporting member, a wedge-shaped member interposed between said table and supporting member, an adjustment screw carried on said supporting member and engaging said wedge-shaped member for moving said wedge-shaped member relatively to said supporting member and table to thereby vary the position of the supporting table relatively to the grinding wheels for controlling the degree to which the said tape is ground by the wheels, clamping means between said supporting member and table for securing the supporting table to the said supporting member in adjusted position, and a rotatable bar carried by said carrier base and having a cam portion for supporting the said supporting member, the said bar being rotatable to permit pivotal movement of the said supporting member and said table carried thereby in a direction away from the grinding wheels without disturbing the position of the table relatively to the supporting member.

3. In an apparatus for reducing the marginal edge portion of a tape including a pair of coaxial spaced grinding wheels, a supporting mechanism for supporting said tape in contact with said grinding wheels for a grinding operation; the said supporting mechanism comprising a stationary base positioned under said wheels, 9. sub-base mounted on said stationary base and adjustable thereon in the direction of the axis of the wheels, a carrier base mounted on said subbase and adjustable thereon in a direction transverse of said axis, a supporting member pivotally mounted at one end to said carrier base and having a cam portion engaging the opposite end of the supporting member for retaining said supporting member in operative position, the said cam portion being movable upon rotation of the bar to permit pivotal movement of the supporting member, a wedge-shaped member slidable on said supporting member, a supporting table mounted upon said wedge-shaped member, a stud fixed to said supporting table and slidably secured to the supporting member to permit adjustment of the table relatively to said supporting member in a vertical direction and to prevent movement of the table relatively to the supporting member in a. lateral direction, and a clamping screw threaded to said stud for clamping the table to the supporting member in adjusted position.

4. In an apparatus for grinding the marginal edge portions of tape including a pair of co-axial spaced grinding wheels, a mechanism for supporting the said tape in contact with the grinding wheels during a grinding operation; the said supporting mechanism comprising a base member fixed in a stationary position under the said grinding wheels, a carrier base mounted on said base member and adjustable thereon longitudinally and transversely with relation to the axis of the said grinding wheels, a supporting member pivotally mounted on said carrier base, positioning means on said carrier base for operativeiy positioning the supporting member relatively to the grinding wheels and permitting retraction of said supporting member from its operative posi tion, a supporting table mounted upon said supporting member for supporting the tape in contact with the grinding wheels, a wedge-shaped member between said supporting table and supporting member for vertically adjusting the table on the supporting member to vary the distance of the supporting table from the grinding wheels for the control of the degree to which the tape is ground, a stud rigidly secured to said table and extending therefrom into an opening in the sup porting member, the said stud fitting snugly in said opening and being vertically slidable therein to prevent lateral displacement and permit vertical adjustment of the said table relatively to said supporting member, and a clamping screw threaded to said stud for clamping the table in adjusted position upon the supporting member whereby the said table may be withdrawn from the grinding wheels by the retraction of the supporting member without the disturbance of the adjustment of the said supporting table relatively to the said supporting member.

EDWARD P. THORSELL.

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